The present invention relates generally to a cell device, and more specifically to a chemical cell device having a positive electrode, a negative electrode, and an electrolyte, capable of generating electricity through chemical reactions, and also capable of electrically charging and discharging.
A chemical cell device usually includes current collecting materials permitting electron movement so as to effect the flowing of electric current, a positive electrode and a negative electrode each comprising an active substance capable of electrically charging or discharging by collecting or producing electrons, an amount of electrolyte allowing smooth flowing of electric current and constituting another place for electrically charging and discharging by adjusting the amount of ions in the electrolyte, and a porous insulating separator provided to prevent short circuit possibly formed between the positive electrode and the negative electrode, but not to impede ion conductivity in the electrolyte.
In order to improve the efficiency of a chemical cell, i.e., to obtain a larger charging capacity for the above-described chemical cell, it is usually necessary to prepare a mutually-facing electrode pair both of which have a large area to obtain a large capacity for electric charging and discharging, also it is necessary to render the distance between the two electrodes as small as possible so as to reduce the internal resistance.
However, in practical use, the size of a chemical cell is often restricted. To satisfy the above-mentioned requirements, it has been suggested to utilize a kind of layer-built cell because it functions as a high-efficient cell without the necessity of making the cell in large size.
One simple form of a layer-built cell comprises a plurality of positive electrodes and a plurality of negative electrodes, all of which are processed into a same form of thin plate and are arranged alternatively so as to form a layer-built structure. Then, all the positive electrodes are connected together by a lead wire, and all the negative electrodes are connected together by another lead wire. In this way, a plurality of electrode pairs are formed, and each electrode pair serves as a single cell. In fact, these electrode pairs may be considered as having connected in parallel, so that the overall capacity of the layer-built cell will increase by increasing such electrode pairs. But, in such a layer-built cell, since it is extremely difficult to completely unify the capacity and the resistance of individual electrodes, there occurs a problem that an electric load is apt to concentrate on one position, causing a damage to the cell device itself.
To overcome the above problem, it is necessary to have all the positive electrodes and all the negative electrodes respectively formed in a continuous integral state, to obtain an electrode pair as shown in FIG. 5. In FIG. 5, reference numeral 1 represents an electrode (positive electrode), 2 represents another electrode (negative electrode), 3 represents a separator interposed between the electrode 1 and the electrode 2, 4 represents mutually-overlaid portions of an identical electrode. As illustrated in FIG. 5, the electrode pair is formed by first letting one electrode lie on top of the other and then folding the two mutually-overlaid electrodes in a predetermined manner as shown in the drawing. Since the two electrodes are all formed in a continuous integral state, it is sure to prevent the electric lead from concentrating on one position.
But, as is understood from FIG. 5, since different portions of a same electrode are forced to face each other, it will be difficult to truly improve the electrical capacity of such a layer-built cell.
In order to avoid the problem of the layer-built cell as shown in FIG. 5, it has been suggested to utilize another layer-built electrode pair 5 as shown in FIG. 6. In FIG. 6, the layer-built electrode pair 5 comprises an electrode 101 (positive electrode) and another electrode 102 (negative electrode) which are laminated together and rolled up so as to form the layer-built cylindrical structure. Either the electrode 101 or the electrode 102 is provided on both sides thereof with a seperator layer (not shown). In the layer-built electrode pair 5 which is constructed in a manner as shown in FIG. 6, each of the electrodes 101 and 102 is formed as a continuous integral body, with one electrode facing the other throughout the whole structure. After incorporating one or more such electrode pairs 5 into a package and filling the package with an electrolyte, another type of layer-built cell different from that shown in FIG. 5 may be obtained.
FIG. 7 indicates that two cylindrical electrode pairs 5 are received in a rectangular parallelepiped package 6, with several vacant spaces 7 formed between the package walls and the electrode pairs 5.
However, a cell structure formed in a manner as shown in FIG. 7, presents a problem that about 20 per cent of the internal space will be unused. To solve this problem, it has been suggested that the shape of the electrode pairs be changed so as to conform to that of the package, or the shape of the package be changed so as to conform to that of the electrode pairs. But, since a product cell is usually received and packed into a rectangular parallelepiped case, such a solution to the above problem has been proved to be neither economical in cost nor practical in use.